Hi,
I've been trying to build a Peltier circuit that I can control with arduino and create cooling ramps. I've never built a circuit before and only have a basic knowledge of electronics.
I've been researching how to do this and attempted to build it. My circuit is basically a PWM signal sent to a motor driver with an LC filter to smoothen the signal. Since very low temperatures are required, I added another Peltier on top of the first one. The top Peltier needs to be driven at a lower voltage to limit the amount of heat produced and effectively lower the temperature. I used a buck converter to do that (probably not the proper way to do this). With this setup, I can reach -53•C (hot side cooled by a waterbath at -15C) However, there are issues:
- For the capacitors, I used 2 electrolytic of 470uF each. At low PWM duty cycle, they burn within seconds. The legs glow and come apart. That's how hot they get. I read about the ESR and the effects of frequency. I played around with the PWM frequency, from below 1kHz to 40kHz, but that didnt solve the issues. I tried several smaller uF and larger uF values without success. Then I read about ceramics capacitors. My local store only had 1 uF. I put a few of these in parallel but now the buck converter doesn't work properly, probably because a few uFs is not enough to smoothen the signal into a DC current for the buck converter. The ceramic capacitors get to about 50C at low duty cycles. I worry that larger ceramic capacitors will get hotter.
- I got the parts from my local electronics store. They sold me an inductor that they said can handle high currents but couldn't tell me the inductance. It's about 7cm wide and long.
- Currently, the PWM frequency is 31372.55 Hz.
- Without being sure what causes the issue, I was going to get another inductor with a known inductance and several low ESR ceramic capacitors of 100 uF.
- The current circuit is being supplied 12v from a 12v 50a power supply. To drive the Peltiers to their full potential, I will be getting a 24v 1000w power supply and a big heatsink. I'll need to keep the current below 25A to avoid killing my motor driver.
The flyback diodes at 15A. There are 2 in parallel.
The circuit is probably not drawn and built properly. Again, this is my first time doing this.
The peltiers: https://cdn.badcaps-static.com/pdfs/...d4c890b119.pdf
Motor driver: https://www.pololu.com/product/1455
Buck converter (ideally I'd find an alternative to using a buck converter): https://www.creatroninc.com/product/...-with-display/
Please let me know if I forgot to mention anything. Thank you for your help!
I've been trying to build a Peltier circuit that I can control with arduino and create cooling ramps. I've never built a circuit before and only have a basic knowledge of electronics.
I've been researching how to do this and attempted to build it. My circuit is basically a PWM signal sent to a motor driver with an LC filter to smoothen the signal. Since very low temperatures are required, I added another Peltier on top of the first one. The top Peltier needs to be driven at a lower voltage to limit the amount of heat produced and effectively lower the temperature. I used a buck converter to do that (probably not the proper way to do this). With this setup, I can reach -53•C (hot side cooled by a waterbath at -15C) However, there are issues:
- For the capacitors, I used 2 electrolytic of 470uF each. At low PWM duty cycle, they burn within seconds. The legs glow and come apart. That's how hot they get. I read about the ESR and the effects of frequency. I played around with the PWM frequency, from below 1kHz to 40kHz, but that didnt solve the issues. I tried several smaller uF and larger uF values without success. Then I read about ceramics capacitors. My local store only had 1 uF. I put a few of these in parallel but now the buck converter doesn't work properly, probably because a few uFs is not enough to smoothen the signal into a DC current for the buck converter. The ceramic capacitors get to about 50C at low duty cycles. I worry that larger ceramic capacitors will get hotter.
- I got the parts from my local electronics store. They sold me an inductor that they said can handle high currents but couldn't tell me the inductance. It's about 7cm wide and long.
- Currently, the PWM frequency is 31372.55 Hz.
- Without being sure what causes the issue, I was going to get another inductor with a known inductance and several low ESR ceramic capacitors of 100 uF.
- The current circuit is being supplied 12v from a 12v 50a power supply. To drive the Peltiers to their full potential, I will be getting a 24v 1000w power supply and a big heatsink. I'll need to keep the current below 25A to avoid killing my motor driver.
The flyback diodes at 15A. There are 2 in parallel.
The circuit is probably not drawn and built properly. Again, this is my first time doing this.
The peltiers: https://cdn.badcaps-static.com/pdfs/...d4c890b119.pdf
Motor driver: https://www.pololu.com/product/1455
Buck converter (ideally I'd find an alternative to using a buck converter): https://www.creatroninc.com/product/...-with-display/
Please let me know if I forgot to mention anything. Thank you for your help!
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